smith



s. SMITH.

Hot-Air Furnace.

No. 79,020.. Patented June 16,1868.,`

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Y IMPROVEMENT IN Hor-AIE Furnaces.

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T0 .AIL WHOM ITMAY CONQERN:

Be it known that I, SIDNYSMITH, of Worcester, in the county of Worcester, and State of Massachusetts, have invented a new and useful Improvement in Furnaces; and I dohereby'declare the folloivingv to be a full, clear, and exact description of the same,.r efercnce being had to thevaccompanying drawings, in which- Figure lis a perspective vie'w of my furnace, with a portion ofthe sidewall removed to exhibit the construction.

Figure 2 is a vertical cross-section of the Samet Figure 3 is a vertical longitudinal section through the centre of the same. Figure 4 is' a plan, with the cover 'of the hot chamber removed. 4 My furnace belongs to that class which lconverts fuel into heat for the purpose of farming and VentilatingV buildings; and4 my invention consists, iirst, in the `use of a number of deilectinglplates, to bring the moving currents of air in contact with` the radiating surface of thc furnace; second, in forming thesaid radiating surv face with a series of corrugations transverse to the direction of the moving crrentsof air;' and, third, in the manner of arranging the air-chamber orreservoir at .the top 'ofthe furnace, and introducing --therhobair pipes thereto. l 4 4 A i i i As heating-furnaces of .the Aclass above mentioned are usually constructed, there is a surrounding space within the outer casing or jacket, more orless large, within which the air may circulate and be exposedtothe action of the heat radiated from the walls of vthe hre-chamber. Atmospheric air is a slow conductor of heat, and from experience it has been found that n 'hen the registers at the ends of the hot-air ductsare opened, a rapid current of air maybe'induced through the hot-air chamberfsurrounding the furnace, and thatthis current will sometimes pass through said chamber so rapidly aslto'make its exit therefrom almost at the same tempera ture as when it entered; `consequently it is frequently impossible to Warm'more than a portion of thephouse at one time. It salso observed that air lwhich has been heated by its passage through the hot-air'chamber of" such a. furnace, has been deprived of its moisture, and itis necessary to supply thisV again by artificial means or, if not so supplied, the air is immediately noticeable as`hot,1dry, and oppressive.`

These disadvantages are remedied in my.`app aratu`s, first, by preventing the passage of: any volume of air through the hot chamber without being brought into close contact with the radiating surface; second, by pro ducing a thorough intercirculation and equalization ofthe temperature of the enclosed air; third, by causing the movingrcurrents of air' to pass 'in close contact withv the radiating surfaceso rapidly that it will not be heated Vto a degree suicicnt to deprive it of it's moisture; fourth, by heating a large volume of air moderately, rather than heating a small volui'ne to a high degree. In furnaces as usually constructed, -the currents of' air move 'with about uniform velocity through the whole extent of the hot-air chamber. In my furnace the velocity is y variable, the air passing most rapidlyover those portions of the radiating surfffce'with .ivhich it comes 'most closely in contact. A

I will now particularly describe its construction and operation.

A is the shell or radiating surface. Within this shell i's placed a re-chamber of any'approved construction,-

and'furnished with suitable doors, through `which fuel, `85e., may be'introduced, and the ashes, dto., be extracted. Theshell A is cast with corrugations, arranged so a's to be transverse to the direction of the moving currents' of air. These corrugations perform' several functions: First, they interrupt, deflect, and cause to interi mingle,tl 1e moving currents;V second, they increase the extent'ot the radiating surface; and, third, they permit expansion and contraction to'take" place with more'uniformityot ell'ect than could be the case if they viera diiierently` arranged. v

If the corrugations are placed vertically, as has hitherto been the practice, so as to be parallelwith the directionfof the moving currents, they form so many grooves or channels, along which currents of air are induced to run; and, While theyincrease the surface of'radiation to somedegree, they d'o not proportionately increase the power'oi the apparatus in imparting heat to a volume of air, because the presence of v the corrugations is favorable to a rapid transit, but not to a thorough mixing of the hot and cold portions of the enclosed airi When the corrugetions are placed transversely to the moving currents, a rapid flow through the hot chamber is prevented, and the hot air is being constantly dedected and thrown dif into the midst of that which is less heated.

The shell A is surrounded at alittle distance by a wall, B, ofbrick or other materialY This wall forms the outer jacket or case, and the enclosed space is the Ihot-air chamber. The deflectingplates C Care secured to the inner sideslof this wall B, and, projecting upward `and inward, reach to within al short distance, say one inch, of the radiating surface A. The edges of these defiectos may be arranged so as to be opposite the highest points onthe shell A, though this is not considered as being material. Above the top of the s hellA, I make a chamber or reservoir, by extending the side walls upward as high as desired,.and I insert-my outlet-pipes D in the sides of this chamber whenever convenient to do so, for the reason that it' is usually cheaper soto insert them, and for' the further reason thatthey are then less likely to inuence each other while in operation.

The upperv set of 'deecting-pl'ates, C, act aspartitions to divide the hot chamber or reservoir above from the hea'ting-chamber below, and they compel the currents of airto enter said chamber or reservoir at the centre remote from the'oriices of the outlet-pipes. v

If the whole space between the radiating surface A and the'lwall B nowhere exceeded in thickness the disvtance between'thev edge of the plateC and vsaid surface A, thefriction of contact would be so great that a coinparatively small volume of air wouldpass through that chamber; but when the general size of th'atchamber is ample, and narrow spaces only occur occasionally, the air wilLow through those' narrow spaces with great rapidity, and will move more slowly through the larger lspaces between said defiectingplates, and the effect will be a rapid ow in' close ,contact with the heated material of the shell A,'so rapid that the air will'. be warmed without being deprived of its moisture.

' By using thedeecting-plates, the formation-of lseparate currents of cool and hot air is'cornplet'e'ly,prevented,

' the repeated passage through the'narrow spaces between deectingplates and the radiating surface effectue-ily -mixing and commngling the air at a uniform temperature. v

The advantages arising from the use of the deflectors C C do not depend upon the corrugated form of the shell, nor upon the presence of an,air-chambe1"above the shell A, nor is the placing of the exit-pipes at the side material thereto, though prefer so to place them, because less costly and more convenient.

Inl furnaces of large size, I insert one or more dues, E E, opening to the external air at the front of the lfurnace,` (either directly intothe apartmentor cold-air duct,) and opening at theopposite end into the hot-air .space behind thefurnace. These ues I construct with corrugated walls, e e, converging and meeting atvthe top, the corrugations being vertical, so as to be transverse to the direction of the moving currents of air; and, in order to increase the surface of radiation, and to deflect and cause the-volumeof` air passing through said iues to 'become' thoroughly mingled, I insert the open-based cones,j`f, at intervals `through the length of the iue,as shown in the figures;` The ues E E pass through the fire-chamber within the`shellA, and the heated products of combustion have access to all sides of them.

The direct-draught iue F is provided .toA facilitate the kindling of a fresh fire, and the diving-dues Gr Gto increase the distance to be traversed by the products of combustion; before they escape' from the furnace into the chimney-Hue; s

, Claims.

1. The she1lA,.corrugated horizontally, as described, in combination with the deecting-plates C C, sub. stantiallyas and for the purpose set forth. l 2. The lues'E, constructed with corrugated walls e, and hollow conesf, substantially as and for 'the purpose set forth. l

3. The ydefiecting-plates C C,or their equivalents, to deflect the upward currents of air against the radiating surfacesof thefurnacei i i t SIDNEY SMITH.

Witnesses:

RD.- O. SMITH, R. S. Tunning. 

